Ultra low Co-doped CeO₂ catalysts for enhanced toluene combustion: Unveiling structure-activity relationships and molecular oxygen activation capability

Developing efficient and durable catalysts for VOCs abatement remains a critical challenge. Herein, we report a Co-doped CeO₂ catalyst (CoCeO₂-400) with ultralow Co loading (1.5 wt%) that achieves a 50% enhancement in toluene combustion efficiency compared to pristine CeO₂-400. Comprehensive characterization reveals the structural evolution of the catalyst. At calcination temperatures ≤ 500 °C, Co^{2 +} is uniformed dispersed within the CeO₂ lattice while higher temperatures (≥ 600 °C) lead to segregated CoO_X formation. The optimized CoCeO₂-400 catalyst exhibits exceptional performance, reaching 90% toluene conversion at 241°C and maintaining satisfactory recyclability and stability at complete conversion temperatures. Through the synergy of advanced characterization techniques and DFT calculations, we established a clear structure-activity relationship: the introduction of Co²⁺ not only increases oxygen vacancy generation but also improves material reducibility. Consequently, a balanced oxygen activation pathway emerges, characterized by a moderate oxygen dissociation barrier (1.68 eV) that ensures swift regeneration of active sites and optimal catalytic performance. Our findings demonstrate the potential of atomic-level structural engineering. Precise dopant integration can dramatically improve catalytic performance, offering a promising strategy for developing energy-efficient environmental catalysts with minimal metal usage.